Fig. 1. Schematic of photoacoustic imaging process

Fig. 2. Schematic of photoacoustic microscopy^[2]

Fig. 3. Schematic of photoacoustic computed tomography^[2]

Fig. 4. Schematic of photoacoustic endoscopy^[2]

Fig. 5. Experimental apparatus and results^[60]. (a) Schematic of the photoacoustic imaging apparatus; (b) time-domain photoacoustic signals; (c) photoacoustic imaging of four-layered document sample with nonoverlapping text; (d) photoacoustic imaging of three-layered document sample with overlapping text

Fig. 6. Experimental apparatus and results^[61]. (a) Schematic of photoacoustic imaging apparatus; (b) detection results of different samples

Fig. 7. Fitted curves and thickness characterization^[62]

Fig. 8. Mesurement of random thickness ultramarine blue layer^[62]. (a) Cross-sectional image of the edge of the sample; (b) normalized amplitude spectrum

Fig. 9. Experimental apparatus and results^[63]. (a) Schematics of the photoacoustic imaging apparatus; (b) identical photoacoustic signal of diffferent media; (c) results of photoacoustic imaging of different samples

Fig. 10. Near-infrared photoacoustic imaging analysis of oil painting^[64]. (a) PA image registered on the RGB image; (b) lines showing the shape of the retouching and cutting; (c) image showing the details of retouching area

Fig. 11. Schematic of the photoacoustic imaging apparatus^[67]

Fig. 12. Photoacoustic imaging results^[70]. (a) Revealing hidden sketch drawings under tempera paint; (b) revealing hidden sketch drawings under limewash coat

Fig. 13. Experimental apparatus and results^[71]. (a) Schematic of photoscoustic imaging apparatus; (b) maximum amplitude change for irradiation with wavelength of 1064 nm; (c) maximum amplitude change for irradiation with wavelength of 1064 nm and 355 nm